U.S. Pat. No. 3,354,238, hereby incorporated herein by reference, discloses and claims a series of acrylic multipolymer compositions which generally constitute a majority of a methyl methacrylate-styrene-acrylonitrile terpolymer and a minor amount of polybutadiene grafted with methyl methacrylate, styrene and acrylonitrile.
While these acrylic multipolymers have proven to be exceptionally attractive in the molding industry for the preparation of thin-walled containers, etc., in some instances the multipolymers do not have a sufficiently high impact strength and moisture vapor transmission to enable them to be used in applications where exceptional impact resistance and resistance to vapor permeation is a necessity rather than just another property. These deficiencies have been overcome by blending specific amounts of vinyl chloride polymers with these multipolymers. While these new compositions function excellently in many applications, it has also been a prime concern of manufacturers to produce a composition which is also flame-retardant while remaining transparent and if such a system could be devised, a long felt need would be satisfied.